For many years surgical wounds and other internal and skin wounds, have been closed using sutures and needles. In more recent times a number of skin stapling instruments have been developed. These instruments apply a series of metal staples to an external wound; that is, a skin wound, to close the wound. In many instances, such skin stapling instruments have replaced the suturing of such wounds. Also, in more recent times instruments have been developed to apply metal fasteners such as staples internally to close internal wounds during a surgical procedure. The primary advantages of the instruments which apply staples to wounds is that they greatly reduce the time required to close the wound and present minimum traumatic effects to improve healing of tissue. Both factors lead to reduced blood loss and improved patient care. Thus, these instruments have considerable medical benefits and economic benefits in surgical procedures. A major disadvantage of closing wounds with metallic staples are that very often the patient requires subsequent diagnostic procedures such as x-rays, cat scanning, and the like, and the metal staples often disrupt such diagnostic procedures. To overcome this last drawback, a number of polymeric fastening systems have been developed which use fasteners made from polymeric materials placed by a suitable instrument to close the wound. Examples of such fastening systems are more fully disclosed in U.S. Pat. Nos. 4,060,089, 4,532,927; 4,532,926; and 4,513,746.
In European patent application No. 84401937.2, Publication No. 0136949, there is disclosed a surgical fastening system made from polymeric materials which has a primary use of closing internal wounds. The system comprises a two-piece fastening member that is a staple which penetrates the tissue to be closed and a retainer or receiver which interlocks with that staple once it has penetrated the tissue to maintain the wound closed. In this patent, the retainers are connected to one another by yieldable links, that is flexible or frangible links. The links are used to maintain the receivers together to assist in loading instruments with the receivers, and it is desired that once applied to the tissue the links break so as not to restrict movement of the tissue.
While such polymeric fastening systems may be made from many different polymer materials, it is desirable that the fasteners be made from absorbable polymeric materials; that is, material that will be hydrolyzed or absorbed by human tissue. By making the fasteners of such absorbable materials, once placed and once the tissue is joined, the material is absorbed by the human body and, hence, no foreign material remains in the human body which may be disruptive and cause complications. It is important to make the fasteners of material that will have sufficient strength to maintain its integrity after it has been placed to hold the tissue together for a sufficient period of time to allow the tissue to heal before the material starts to lose its strength and be absorbed.
What we have discovered is a specific configuration of a fastening system comprising staples and receivers which not only provides for ease and loading of the instruments with the fasteners and, hence, the desired economics, but also when made from absorbable polymeric materials, has sufficient strength to maintain the desired configuration until the tissue has healed. It is a further object of the present invention to provide a configuration which will move or flex with the tissue that has been joined yet will maintain its configuration and aid in the healing or joining of the tissue. We have discovered that by joining the receivers in a two-piece absorbable polymeric system in a specific manner, not only do we get the economic benefits in manufacture and the medical benefits in reducing the time for the surgical procedure, but unexpectedly we obtain more desirable healing characteristics when using our new fastening system to join wounds.